running nginx as a reverse proxy

This isn't directly rails related..but I am hoping some of you might
have tried this for sure so why not ask.

I am using passenger with nginx to serve my rails app on a virtual
slice host. I am considering putting a reverse proxy for serving
static content as well as handling etagged actions.

1 - Can I use my existing nginx installation and just change it to a
reverse proxy? Do I even need a web server? What would a typical
architecture look like in this case?

nginx rev-proxy -> nginx web server -> passenger?

or

nginx rev-proxy -> passenger?

2 - Is nginx the best choice in this case?

3 - Can my reverse proxy reside on the same slice?

Thanks